I recently got what I THOUGHT was 2 female spiny mice (atleast thats what the breeder told me). Well last night i noticed one of my mice chasing the other and then i realized they were mating. I cannot find any info on this and I was wondering what i should do. Any and all help is welcome.

Chances are that if you got them from an experienced breeder, then you do have two girls. Humping is part of fighting for dominance, they are deciding who will be the alpha mouse. If any open wounds or blood appears you will need to separate them but fighting for dominance is fine. Just incase, search for a mouse sexing diagram on google images, and check the genders for yourself, if you do have a male and a female, watch out for sighns of pregnancy such as nesting, prominant nipples, and a bigger belly. Im not sure on the gestation but I am sure one of our mice owners can tell you that It would also be a good idea to separate the two if you do have a male and a female